Enhancement of transcription factor, USF, binding to the adenovirus major late promoter: effect of dithiothreitol and high mobility group protein-1.
Up-stream stimulatory factor (USF)1 is a human transcription factor which binds specifically to the E-box in the Ad MLP located at - 58 from the start site. The nature of USF binding on a Ad MLP DNA fragment was investigated in the presence of DTT and also in the presence of purified HMG-1 using electrophoretic mobility shift assay. We show that the binding capacity of USF for the E-box increases significantly with increasing DTT concentrations. At the higher DTT levels, a second USF-DNA complex is formed in which there is co-occupation of both the E-box and the initiator sequence. The stability of the second complex is largely refractory to an excess of unlabeled oligonucleotide which contains the initiator sequence. These findings indicate a cooperative binding interaction between USF ligands bound simultaneously at the E-box and the Inr sequence. Two models are proposed which are consistent with these data. Furthermore, experiments indicate that the presence of HMG-1, a nuclear protein known to influence transcriptional activity, increases USF binding activity at the E-box by as much as 100%. These findings indicate that both reducing conditions and HMG-1 may act as modulators of USF-regulated transcription.
Marmillot
P
P
Department of Chemistry, Bowling Green State University, OH 43403, USA.
Scovell
W
W
D000256:Adenoviridae / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology*; D006609:High Mobility Group Proteins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D051720:Upstream Stimulatory Factors; D014764:Viral Proteins
D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; C051096:MLTF protein, adenovirus; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; D014764:Viral Proteins; D004229:Dithiothreitol